Release of Mycoplasma pneumoniae substances after phagocytosis by guinea pig alveolar macrophages.
Antibody-opsonized Mycoplasma pneumoniae cells with various radioactive markers were sedimented onto monolayers of guinea pig alveolar macrophages (AM). After 2 h of incubation, about 50% of the activity of [3H]palmitate-labeled mycoplasmas was associated with AM. Nonspecific attachment of the opsonized mycoplasmas to AM-free plastic surface areas was negligible. The occurrence of phagocytosis was proven by electron microscopy and monitoring of AM surface-bound antigen by 125I-labeled F(ab)2 fragments. The activity of [3H]palmitic acid-labeled mycoplasmas was only slowly released into the supernatant. About 55% of the activity remained AM-associated up to 70 h after phagocytosis. After phagocytosis of [3H]thymidine-labeled cells, about 70% of the radioactivity found non-precipitable by trichloracetic acid. 3H-amino acid-labeled protein was released to 50% within 8 h. Supernatants and AM were tested for M. pneumoniae antigen with enzyme-linked immunosorbent assay. Considerable amounts of antigenically active material could be found in the supernatant within 8 h. This antigen was totally inactivated by heat (80 degrees C). Trypsin treatment (1 mg/ml, 10 min) reduced the antigenicity by 80%. The results suggest a selective release of microbial material after phagocytosis.
D000818:Animals; D000942:Antigens, Bacterial; D001426:Bacterial Proteins / Q000378:metabolism; D003571:Cytochalasin B / Q000494:pharmacology; D004269:DNA, Bacterial / Q000378:metabolism; D006168:Guinea Pigs; D006358:Hot Temperature; D050356:Lipid Metabolism; D008264:Macrophages / Q000276:immunology*; D009177:Mycoplasma pneumoniae / Q000032:analysis / Q000276:immunology*; D011650:Pulmonary Alveoli; D014357:Trypsin / Q000494:pharmacology
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D003571:Cytochalasin B; D014357:Trypsin